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Abstract:

Particular embodiments disclosed herein relate to methods, compositions,
and systems relating generally to heating, ventilation, and air
conditioning (HVAC) systems, and more specifically, to HVAC systems that
transfer sensible and/or latent energy between air streams, humidify
and/or dehumidify air streams. In certain embodiments, a polymeric
membrane is utilized for fluid exchange, with or without an additional
support. Certain embodiments allow for individual regulation of air
temperature and humidity.

Claims:

1. A system comprising:a mass exchanger having a first surface and a
second surface;a gas flow structure configured to direct a flow of a gas
mixture to pass by in contact with the first surface of the mass
exchanger; anda liquid flow structure configured to direct a flow of a
liquid mixture to pass by in contact with the second surface of the mass
exchanger, the mass exchanger configured to receive a first gas out of
the gas mixture including at least the first gas and a second gas and to
transfer the first gas therethrough to the second surface to be accepted
by the liquid mixture without transferring the second gas therethrough
when the gas mixture is in contact with the first surface, when the
liquid mixture is in contact with the second surface, and when the gas
mixture and the liquid mixture have first predetermined conditions, the
mass exchanger configured to receive the first gas from the liquid
mixture and to transfer the first gas therethrough from the second
surface to the first surface to be accepted by the gas mixture when the
liquid mixture is in contact with the second surface, when the gas
mixture is in contact with the first surface, and when the gas mixture
and the liquid mixture have second predetermined conditions.

2. The system of claim 1 further including a heat exchanger having an
intake and an exit, the heat exchanger coupled to receive flow of the
liquid mixture into the intake of the heat exchanger and output flow of
the liquid from the exit of the heat exchanger.

3. The system of claim 2 wherein the liquid flow structure has an intake
and an exit, the liquid flow structure configured to direct the flow of
the liquid mixture from the intake to the exit.

4. The system of claim 3 wherein the liquid flow structure is coupled to
the heat exchanger for the intake of the liquid flow structure to receive
flow of the liquid mixture from the exit of the heat exchanger.

5. The system of claim 3 wherein the liquid flow structure is coupled to
the heat exchanger for the intake of the heat exchanger to receive flow
of the liquid mixture from the exit for the liquid flow structure.

6. The system of claim 1 wherein the mass exchanger includes a selective
transfer membrane having a first surface and a second surface, the first
surface of the mass exchanger being the first surface of the selective
transfer membrane and the second surface of the mass exchanger being the
second surface of the selective transfer membrane.

7-8. (canceled)

9. The system of claim 1 wherein the mass exchanger includes a selective
transfer membrane having a first surface and a second surface and a
porous support having a first surface and a second surface, the second
surface of the selective transfer membrane being positioned adjacent to
the first surface of the porous support, the first surface of the mass
exchanger being the first surface of the selective transfer membrane and
the second surface of the mass exchanger being the second surface of the
porous support.

10. The system of claim 9 wherein the selective transfer membrane is a
composition including an ionomeric polymer.

12. The system of claim 9 wherein the porous support structure includes a
porosity of at least about 30%.

13. The system of claim 12 wherein the porous support includes polethylene
silica.

14. The system of claim 1 wherein the mass exchanger includes a selective
transfer membrane having a first surface and a second surface and a
porous support having a first surface and a second surface, the second
surface of the porous support being positioned adjacent to the first
surface of the selective transfer membrane, the first surface of the mass
exchanger being the first surface of the porous support and the second
surface of the mass exchanger being the second surface of the selective
transfer membrane.

15-16. (canceled)

17. The system of claim 14 wherein the porous support structure includes a
porosity of at least about 30%.

18. The system of claim 17 wherein the porous support includes polethylene
silica.

19-35. (canceled)

36. A method comprising:providing a selective transfer membrane having a
first surface and a second surface;providing a porous support having a
first surface and a second surface, the first surface of the porous
support being adjacent to the second surface of the selective transfer
membrane;exposing the first surface of the selective transfer membrane to
a gas mixture including at least a first gas and a second
gas;transferring a portion of the first gas through the selective
transfer membrane without substantially transferring the second
gas;transferring the portion of the first gas through the porous support
without substantially transferring the second gas;exposing the second
surface of the porous support to a first liquid; andaccepting the portion
of the first gas into the first liquid as a second liquid.

37. The method of claim 36 wherein providing the porous support includes
providing the porous support with at least some surface portions that are
substantially hydrophobic.

38. The method of claim 37 wherein exposing the porous support to a first
liquid includes exposing as a flow of the first liquid.

39. The method of claim 37 wherein exposing the selective transfer
membrane to a gas mixture includes exposing as a flow of the gas mixture.

40. The method of claim 37 wherein the first gas is substantially polar
and the second gas is substantially non-polar.

41. The method of claim 37 wherein the first gas is water vapor and the
second gas is oxygen.

42. The method of claim 37 wherein the first liquid is water.

43. The method of claim 37 wherein the second liquid is water.

44. A method comprising:providing a selective transfer membrane having a
first surface and a second surface;providing a porous support having a
first surface and a second surface, the second surface of the porous
support being adjacent to the first surface of the selective transfer
membrane;exposing the first surface of the porous support to a gas
mixture including at least a first gas and a second gas;transferring a
portion of the first gas and the second gas through the porous
support;transferring the portion of the first gas through the selective
transport membrane without substantially transferring the second
gas;exposing the second surface of the selective transport membrane to a
first liquid; andaccepting the portion of the first gas into the first
liquid as a second liquid.

45-51. (canceled)

52. A method comprising:providing a selective transfer membrane having a
first surface and a second surface;providing a porous support having a
first surface and a second surface, the first surface of the porous
support being adjacent to the second surface of the selective transfer
membrane;exposing the first surface of the selective transfer membrane to
a liquid;transferring a portion of the liquid through the selective
transfer membrane as a first gas;transferring the first gas through the
porous support;exposing the second surface of the porous support to a
second gas; andaccepting the first gas into the second gas.

53. The method of claim 52 wherein the portion of the liquid has a
chemical composition different than at least some other portions of the
liquid.

54-57. (canceled)

58. The method of claim 52 wherein the first gas is water vapor and the
second gas is air.

59. (canceled)

60. A method comprising:providing a selective transfer membrane having a
first surface and a second surface;providing a porous support having a
first surface and a second surface, the second surface of the porous
support being adjacent to the first surface of the selective transfer
membrane;exposing the first surface of the porous support to a
liquid;transferring a portion of the liquid through the porous support as
a first gas;transferring the first gas through the selective transfer
membrane;exposing the second surface of the selective transfer membrane
to a second gas; andaccepting the first gas into the second gas.

61. (canceled)

62. The method of claim 60 wherein providing the porous support includes
providing the porous support with at least some surface portions that are
substantially hydrophobic.

63-66. (canceled)

67. The method of claim 62 wherein the liquid is water.

68. A system comprising:a plurality of units coupled together to each
receive a flow of a liquid mixture and a flow of a gas mixture, each unit
including:a mass exchanger having a first surface and a second surface;a
gas flow structure configured to direct at least a portion of the flow of
a gas mixture to pass by in contact with the first surface of the mass
exchanger; anda liquid flow structure configured to direct at least a
portion of the flow of the liquid mixture to pass by in contact with the
second surface of the mass exchanger, the mass exchanger configured to
receive a first gas out of the gas mixture including at least the first
gas and a second gas and to transfer the first gas therethrough to the
second surface to be accepted by the liquid mixture without transferring
the second gas therethrough when the gas mixture is in contact with the
first surface, when the liquid mixture is in contact with the second
surface, and when the gas mixture and the liquid mixture have first
predetermined conditions, the mass exchanger configured to receive the
first gas from the liquid mixture and to transfer the first gas
therethrough from the second surface to the first surface to be accepted
by the gas mixture when the liquid mixture is in contact with the second
surface, when the gas mixture is in contact with the first surface, and
when the gas mixture and the liquid mixture have second predetermined
conditions.

[0003]The present invention relates generally to the field of heating,
ventilation, and air conditioning (HVAC).

[0004]2. Description of the Related Art

[0005]Existing HVAC systems use heat of condensation and/or heat of
vaporization of a liquid, such as water, to adjust temperature and
humidity within a structure such as a dwelling, building, vehicle or
other region such as for a localized environment or functioning
apparatus. Conventional HVAC systems can have evaporative cooling towers,
which dissipate heat carried by a liquid, such as water, by evaporating a
portion of the liquid.

[0006]Unfortunately, the evaporative cooling towers can be costly to
maintain involving cleaning of evaporative surfaces and remedying build
up of toxic salts and metals in water supplies. Other challenges are
involved when attempts are made to scale down evaporative cooling towers
for smaller sized applications. Often smaller scaled operations are
forced to forego use of evaporative cooling towers because of size
scaling issues. Consequently, efficiency of these smaller applications
can suffer.

[0007]Conventional HVAC systems can also use condensing heat exchangers to
remove heat from a region by condensing out a portion of a gas, such as
water vapor, present in the region. The conventional condensing heat
exchangers provide surface area for condensation to occur. Unfortunately,
liquid already condensed on a portion of the surface can interfere with
further condensation thereby hindering efficiencies.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0008]FIG. 1 is a schematic view of a membrane based mass exchanger
according to the present invention showing a first fluid flow
configuration.

[0009]FIG. 2 is a schematic view of the mass exchanger of FIG. 1 showing a
second fluid flow configuration.

[0010]FIG. 3 is a schematic view of the mass exchanger of FIG. 1 used in a
liquid-to-gas phase-change mode.

[0011]FIG. 4 is a schematic view of the mass exchanger of FIG. 1 used in a
gas-to-liquid phase-change mode.

[0012]FIG. 5 is a schematic view of the mass exchanger of FIG. 1 in a
membrane-only implementation.

[0013]FIG. 6 is a schematic view of the mass exchanger of FIG. 1 in a
gas-side membrane implementation of a dual layer version of the mass
exchanger of FIG. 1.

[0014]FIG. 7 is a schematic view of the mass exchanger of FIG. 1 in a
liquid-side membrane implementation of a dual layer version of the mass
exchanger of FIG. 1.

[0015]FIG. 8 is a perspective view of a manifold style of mass exchanger
using multiple tubular cartridges to convey the liquid flow.

[0016]FIG. 9 is a top plan cross-sectional view of an individual tubular
cartridge from the mass exchanger of FIG. 8.

[0018]FIG. 10 is an exploded perspective view of a plate style of a
membrane-only implementation of the mass exchanger.

[0019]FIG. 11 is a schematic view of a first implementation of an enhanced
HVAC system.

[0020]FIG. 12 is a schematic view of a second implementation of the
enhanced HVAC system.

[0021]FIG. 13 is a graph of exemplary efficiencies of an implementation of
the enhanced HVAC system.

[0022]FIG. 14 is a graph of exemplary performance characteristics of an
implementation of the mass exchanger.

[0023]FIG. 15 is a psychometric chart used to describe exemplary
performance of a gas-to-liquid phase change mass exchanger (an enthalpy
absorber) within the enhanced HVAC system.

DETAILED DESCRIPTION OF THE INVENTION

[0024]An enhanced HVAC system and method incorporates one or more membrane
based mass exchangers along with conventional components to provide
potential maintenance and efficiency advantages. The mass exchangers
include a selective transport membrane that allows only one or more
selected liquids and gases to pass therethrough.

[0025]When used in a liquid-to-gas phase-change mode (an enthalpy
desorber) as an alternative to a conventional evaporative cooling tower,
a portion of a liquid, such as water from a water stream, is allowed to
pass through the membrane of the mass exchanger as a gas without need of
a conventional evaporative surface thereby offering potential reductions
in maintenance burdens and potential greater ease in applying to smaller
sized applications.

[0026]When used in a gas-to-liquid phase-change mode (an enthalpy
absorber) as an alternative to a conventional condensing heat exchanger,
a portion of a gas, such as water vapor, is allowed to pass through the
membrane as the gas, such as water vapor, and to condense directly into a
liquid, such as a flowing water stream, without need of a conventional
condensation surface thereby offering potential increases in
efficiencies.

[0027]Even though the function of the mass exchanger as enthalpy desorber
and enthalpy absorber differ, the designs of the mass exchangers do not
differ in significant detail. Each mass exchanger includes a membrane
between a moving stream of water and a moving stream of air. In one
embodiment, the membrane through such implementations has a layer of
specialized ionomeric polymer and optional hydrophobic microporous
support creates a selectively permeable barrier. The membrane has the
ability to exclude many airborne organic and/or inorganic particulates
and/or gases such as oxygen, nitrogen, argon, carbon dioxide, or others,
while selectively transferring liquid, such as water. This ability allows
the exchanger to desorb only moisture from a moving stream of water that
has a temperature that is above the wet bulb temperature of the moving
air stream in contact with the membrane.

[0028]The membrane protects the coolant water from contamination reducing
or eliminating the need for chemicals to prevent biological contamination
such as mold growth. This minimizes the maintenance that the system
requires. The membrane also does not change its transport properties as
the dissolved solids content increases. Higher concentrations of salt or
other metals within the circulating water can be tolerated by this
system. The reduced levels of chemicals, resistance to biological
contamination and tolerance to dissolved solids allow disposal of the
circulating water down a municipal drain. In addition, the enthalpy
absorber is a net producer of filtered water as it absorbs moisture from
the atmosphere. This water can be pumped into the enthalpy desorber
reservoir to reduce the concentration of dissolved solids that are
circulating.

[0029]In particular implementations, the enthalpy desorber fulfills a role
of an evaporation tower in a large chilled water system of conventional
design. Evaporation of warm water through the selective membrane
transfers latent energy to the uncontrolled outside air, removing that
energy from the conditioning system. This evaporative cooling confers a
substantial performance advantage over typical sensible-only heat
exchangers used in the vast majority of applications. Sensible heat
exchangers operate with their working fluid, usually an inert refrigerant
at high pressure, at temperatures higher than the dry bulb temperature of
the uncontrolled outside air to ensure heat rejection into the warm
outside air. The enthalpy desorber functions as long as the water
temperature is above the wet-bulb temperature of the air, allowing an
approximately 20-30 Degrees Celsius reduction in the condensing
temperature of the refrigerant. Since the condensing temperature is
directly linked to the refrigerant pressure this translates into a
dramatic reduction in the mechanical work input at the refrigerant
compressor.

[0030]The water desorption will lower the temperature of the moving stream
of water through the heat of evaporation. Sensible energy is also
transferred through the direct contact of water and air to the membrane
which will conduct thermal energy.

[0031]As described below, the membrane used can be made from a number of
materials such as a layer of specialized ionomeric polymer. The optional
support described can be made from hydrophobic or hydrophilic microporous
support. The combination of membrane and support can create a selectively
permeable barrier. As with the mass exchanger being in the gas-to-liquid
phase change mode, also known as an enthalpy absorber, the liquid
temperature, such as of a moving water stream, is below the dew point of
the gas, such as containing air and water. The gas flow diffuses through
the support into the membrane, such as an ionomeric polymer, and
condenses directly into the fluid flow, such as a water stream. This
condensing vapor can warm a water stream as it returns to a refrigerant
heat exchanger. Sensible (thermal) energy also can be transferred by the
membrane between an air stream and the water stream.

[0032]The membrane can operate bi-directionally. If a moving liquid (e.g.
water) stream is above the wet bulb temperature of the moving air stream
and preferentially above the sensible dry bulb temperature of the air
stream, liquid (e.g. water) will desorb from the moving stream of water
into the moving stream of air. The water desorption will cool the moving
water stream through the heat of vaporization providing most of the
energy transfer. Again, sensible energy is also transferred through the
direct contact of air and water to the membrane which will conduct
thermal energy.

[0033]In a preferred embodiment, the ionomeric polymers that can make up
the membrane typically have equivalent acid molecular weights below 1200
units, exhibit high selectivity for water, and form uniform thin
structures that can be free standing or laminated or otherwise attached
to an optional support. In certain preferred embodiments, the ionomers
also have chemistries that allow radiation or chemical crosslinking to
immobilize the molecules within the membrane and confer specialized
mechanical and permeation properties. The membranes made from these
ionomers have the ability to exclude many airborne organic and/or
inorganic particulates and/or gases such as oxygen, nitrogen, argon,
and/or carbon dioxide while selectively transferring liquid, such as
water. Since the membrane(s) are typically thin, a support is used when
the mechanical forces and stresses require it. The support can have the
characteristics of hydrophobicity or hydrophilicity depending on the
specific requirements of the application. In addition these supports have
high porosity thus allowing transfer of gas across the support. The
porosity can vary from 10% to 99.99% by weight or volume or greater. In
these preferred embodiments, the membranes allow the mass exchanger to
absorb moisture into a moving stream of liquid (e.g. water) that has a
temperature that is less than the dew point of the air stream in contact
with the membrane. The absorption of the liquid (e.g. water) will raise
the temperature of the moving stream of liquid (e.g. water) through the
heat of condensation. Sensible energy is also transferred through the
direct contact of air and water to the membrane which will conduct
thermal energy.

[0034]In one preferred embodiment, the membrane comprises at least one
layer of ionomeric organic-inorganic hybrid polymer bonded to a
hydrophobic microporous support. This ionomeric layer which is also known
as a stand-alone membrane is described as a macromolecule that has
undergone modification, such as sulfonation, phosphorylation, or
amidization. The sulfonation, phosphorylation, or amidization covalently
bonds ionic groups to the macromolecule. These ionic groups are balanced
by an opposite polarity free ion that is held in place by the Coulombic
force that accompanies opposite polarity charges. Thus the molecule has
no net charge yet has a high charge density consisting of balanced
covalently bound positive charges and free negative ions (sulfonated or
phosphorylated) or covalently bound negative charges and free positive
ions (amidated).

[0035]The mass exchangers may be constructed in one of any number of
forms. One form of the mass exchanger uses membrane comprising cartridges
shown below that can be thought of flattened oblong tubes. Here the
moving air stream passes over the outside of the cartridge while the
water stream is routed through the inside of the cartridge. In the
cartridge design the water can be in direct contact with the membrane or
have an air gap between the water stream and the membrane. The cartridge
system simplifies the exchanger construction.

[0036]A second form of the mass exchangers is a prismatic plate design
shown below. Here dividers called "flow fields" create water channels and
air channels on opposite sides of the membrane. These dividers, typically
rectangular or square in shape, have water and air distribution features
called plenums. Each membrane layer has a flow field on either side of it
delivering air and water to its faces. Flow fields and membrane are
stacked prismatically and bolted end plates complete the exchanger. Water
lines are coupled through the end plates to the water plenums on each
flow field, which then distributes the water across the ionomeric face of
the membrane. The air plenums allow air from outside the exchanger to
pass over the opposite face of the membrane.

[0037]The simplified construction of the cartridge form of the exchanger
system results from looser tolerances for the cartridges. In the
prismatic plate design example the seals and membrane support are
dependant on each flow field being uniformly thick and having membrane
contact surfaces with are highly parallel across each face compared to
the opposing face. A deviation from thickness or parallelism can create
sealing problems if too thin or crush the membrane if too thick or
non-parallel. The cartridges seal independently, with no clamping force
being transmitted from one to another, and do not need to be held to such
tight tolerances.

[0038]An exemplary mass exchanger 100 is shown in FIG. 1 as having a
gas-side surface 100a and a liquid-side surface 100b. The mass exchanger
100 is depicted as being exposed to counter-directional flows directed by
flow structures 101, such as channels, piping, plenums, and the like,
with the gas-side surface 100a being exposed to a gas flow 102 and the
liquid-side surface 100b being exposed to a liquid flow 104 in a
direction substantially opposite to the gas flow.

[0039]The mass exchanger 100 is depicted in FIG. 2 as being exposed to
common-directional flows directed by the flow structures 101 with the
gas-side surface 100a being exposed to the gas flow 102 and the
liquid-side surface 100b being exposed to the liquid flow 104 in a
direction substantially the same as the gas flow.

[0040]The mass exchanger 100 is depicted in FIG. 3 as being in the
liquid-to-gas phase-change mode in which liquid from the liquid flow 104
passes through the mass exchanger as gas 106 to join with the gas flow
102.

[0041]The mass exchanger 100 is depicted in FIG. 4 as being in the
gas-to-liquid phase-change mode in which gas from the gas flow 102 passes
through the mass exchanger as a gas 108 to condense into the liquid flow
102.

[0042]The mass exchanger 100 is depicted in FIG. 5 as being in a
membrane-only implementation of the mass exchanger having a selective
transport membrane 110 with a first surface of the membrane being the
gas-side surface 100a of the mass exchanger and a second surface of the
membrane being the liquid-side surface 100b of the mass exchanger. The
gas-side surface 100a is shown being exposed to the gas flow 102 and the
liquid-side surface 100b is shown being exposed to the liquid flow 104
with the gas flow and the liquid flow shown as either counter-directional
or common-directional flows.

[0043]The mass exchanger 100 is depicted in FIG. 6 as being in a gas-side
membrane implementation of a dual layer version of the mass exchanger
with the selective transport membrane 110 coupled with a support 112. A
first surface of the membrane 110 is the gas-side surface 100a of the
mass exchanger and a first surface of the support 112 is the liquid-side
surface 100b of the mass exchanger. The gas-side surface 100a is shown
being exposed to the gas flow 102 and the liquid-side surface 100b is
shown being exposed to the liquid flow 104 with the gas flow and the
liquid flow shown as either counter-directional or common-directional
flows.

[0044]The mass exchanger 100 is depicted in FIG. 7 as being in a
liquid-side membrane implementation of a dual layer version of the mass
exchanger with the selective transport membrane 110 coupled, such as
through a hermetic seal, with a support 112. A first surface of the
support 112 is the gas-side surface 100a of the mass exchanger and a
first surface of the membrane 110 is the liquid-side surface 100b of the
mass exchanger. The gas-side surface 100a is shown being exposed to the
gas flow 102 and the liquid-side surface 100b is shown being exposed to
the liquid flow 104 with the gas flow and the liquid flow shown as either
counter-directional or common-directional flows.

[0045]A manifold style of the gas-side membrane implementation of the dual
layer version of the mass exchanger 100 is shown in FIG. 8 as having a
plurality of the mass exchangers coupled with an intake fluid manifold
122 and an exit manifold 124. Each of the mass exchangers 100 has its own
separate membrane. As shown in FIGS. 9 and 9A, the membrane 110 is
located on the exteriorly located. A lattice 125 may be included to
provide rigidity where needed. The channels 126 receive a respective
portion of the liquid flow 104 from the intake manifold 122 and to
channel the liquid flow to the exit manifold 124. The mass exchangers 100
are spaced sufficiently apart to allow for passage of the gas flow 102
therebetween. An optional divider 127 may be present, as well as an
optional coupler 128 that may couple the cartridge and the manifold.

[0046]A plate style of a membrane-only implementation of the mass
exchanger 100 is shown in FIG. 10 has having a gas plate 132, a liquid
plate 134, and the membrane 110 therebetween. The depicted plate style of
the mass exchanger 100 allows for stacking together of a plurality of
such mass exchangers so that in an alternating fashion an instance of the
gas plate 132 is positioned in juxtaposition with an instance of the
liquid plate 134 (with an instance of the membrane 110 positioned
therebetween), which is positioned in juxtaposition with another instance
of the gas plate 132 (with another instance of the membrane positioned
therebetween) and so on,

[0047]The gas plate 132 has channels 136 to allow for the gas flow 102 to
move past the gas-side 110a of the two instances of the membrane 110
positioned on either side of the gas plate and exit therefrom. The gas
plate 132 further includes an intake plenum aperture 138a and an exit
plenum aperture 138b that pass the liquid flow 104 therethrough to allow
for stacking of a plurality of the depicted plate style mass exchanger
100. The membrane 110 also includes an intake plenum aperture 139a and an
exit plenum aperture 139b that pass the liquid flow 104 therethrough to
allow for stacking of a plurality of the depicted plate style mass
exchanger 100.

[0048]Each of the liquid plates 134 in a stack of the depicted plate style
mass exchangers 100 has channels 140 to allow the liquid flow 104 to move
past the liquid-side 100b of both of the membranes 110 adjacent to the
liquid plate. Each of the liquid plates 134 in a stack of the depicted
plate style mass exchangers 100 has an intake plenum aperture 142a and an
exit plenum aperture 142b. The intake plenum aperture 142a receives the
liquid flow 104 from one or both of the intake plenum apertures 139a of
the membranes 110 adjacent to the liquid plate. The exit plenum aperture
142b delivers the liquid flow 104 to one or both of the exit plenum
apertures 139b of the membranes 110 adjacent to the liquid plate. The
intake plenum aperture 142a of the liquid plate 134 delivers the liquid
flow 104 to the channels 140 that In turn deliver the liquid flow 104 to
the other of the exit plenum aperture 142b of the liquid plate. The
optional gaskets 145 may seal the plates.

[0049]A first implementation 150 of an enhanced HVAC system is shown in
FIG. 11 and has a first region 152 in which is located a conventional air
handling unit (AHU) 154 and a second region 156 in which is located one
of the mass exchangers 100 configured in the liquid-to-gas phase-change
mode. The AHU 154 is part of a first loop 158, which uses a gas working
fluid to receive heat from the first region through the AHU. The first
loop 158 further includes a vapor compressor 160, a gas-to-liquid heat
exchanger 162, and an expansion valve 164. The vapor compressor 160
receives heated gas working fluid from the AHU 154 and compresses the gas
working fluid to be sent on to the gas-to-liquid heat exchanger (HX) 162
to release heat from the gas working fluid to a liquid, such as water,
recirculating in a second loop 166.

[0050]The second loop 166 further includes an instance of the mass
exchanger (MX) 100 configured in the liquid-to-gas phase-change mode, a
liquid reservoir 168, and a circulation pump 170. The gas flow 102 from
gas found in the second region passes through the mass exchanger 100 by
which a portion of the recirculation liquid in the second loop 166 is
transferred as a gas into the gas flow thereby releasing heat from the
recirculation liquid to the gas of the second region. The liquid levels
of the liquid reservoir 168 are controlled through a supply line 172 and
a drain line 174 to maintain an adequate amount and temperature of the
circulating fluid in the second loop 166. The recirculation pump 170
moves the circulating fluid through the second loop 166.

[0051]A second implementation 180 of an enhanced HVAC system is shown in
FIG. 12 and has a first region 182 which includes part of a first (e.g.
chilled water) loop 184, a second region 186, which includes part of the
second loop 166, and a third (e.g. refrigerant) loop 187 that could be
located in the first region, the second region, or elsewhere. Located in
the first region 182 are a plurality of the mass exchangers (MX) 100
configured in the gas-to-liquid phase-change mode. Located in the second
region 186 is at least one of the mass exchangers 100 configured in the
liquid-to-gas phase-change mode as further described above in conjunction
with the description of the second loop 166.

[0052]The first loop 184 further includes a reservoir type heat exchanger
(e.g. chilled water reservoir) 188, and recirculation pumps 190. The gas
flow 102 from gas found in the first region 182 passes through the mass
exchangers 100 by which a portion of the gas flow 102 is transferred as a
liquid into the liquid flow 104 through each of the mass exchangers
thereby adding heat from the gas flow to the liquid flow. The liquid flow
104 moves through the first loop 184 to a reservoir type liquid-to-gas
heat exchanger 188 where heat is transferred to a gas working fluid in
the third loop 187. The liquid levels of the reservoir type heat
exchanger (chilled water reservoir) 188 are controlled through a supply
line 192 and a drain line 194 to maintain an adequate amount and
temperature of the circulating fluid including the liquid flow in the
first loop 184. The recirculation pumps 190 move the circulating fluid
through the first loop 184.

[0053]The third loop 187 includes the reservoir type heat exchanger 188,
the vapor compressor (VC) 160, the heat exchanger (HX) 162, and an
expansion valve 164. After the heat exchanger 204 transfers heat to the
refrigerant in the third loop 187, at least a portion of the heat is
further transferred to the fluid in the second loop 166 as described
above. FIG. 12 shows a reservoir type heat exchanger 188 in the first
loop 184 and separate heat exchanger 162 and reservoir 168 in the second
loop 166. The first loop 184, also known as a chilled water loop, could
be designed with a separate heat exchanger and reservoir and conversely
the second loop 166, also known as the hot water loop, could use a
reservoir type heat exchanger. The selection of the type of heat
exchanger is applications and performance based and options include
tube-in-tube, shell-and-tube, finned tube, coil-in-reservoir, and plate
style exchangers among other choices. The reservoir tank 168 can store
chilled water and/or ice for the second loop 166. This water and/or ice
later allows the system to circulate cold water and absorb enthalpy from
the controlled enclosure for a limited time without needing to engage the
third (refrigerant) loop 187. This adds a function to the air conditioner
system that is not normally present and if used further increases the
efficiency of the system.

[0054]Shown in FIG. 13 is a theoretical model of a system that uses the
mass exchangers 100 both in the gas-to-liquid phase-change mode and the
liquid-to-gas phase-change mode. The model shows how the annual seasonal
energy efficiency ratio varies with outside ambient temperature.

[0055]The energy efficiency ratio measures the instantaneous system
efficiency and is the cooling capacity in Btu/hr divided by the watts of
power consumed for a specific outdoor temperature. The bottom curve is
the United States federally mandated 2007 minimum efficiency. The middle
curve is the case where the air conditioning system only uses the
desorber. This is equivalent to the case where an air conditioning system
uses an evaporative cooling tower. The top curve represents the case
where an air conditioning system uses both an absorber and desorber. At
standard ARI summer conditions of 35 degrees Celsius (95 degrees
Fahrenheit) the system will have an energy efficiency ratio of 22 to 23.
As can be seen from the curves the air conditioning system is much more
tolerant of high ambient operating temperatures using the enthalpy
absorber and desorber.

[0056]Present implementations are concerned with improving heat transfer
to and from air through the use of the phase change of water from a gas
to liquid and from liquid to a gas. The mass exchanger 110, also known as
a membrane-based enthalpy exchanger, can be used to absorb and desorb
sensible and latent heat into the liquid flow 104, such as streams of
moving water, to transfer heat from within an enclosure to the outside
environment. This process can work in either direction so that if desired
heat can be brought into an enclosure from an outside environment.

[0057]The system can be configured with additional heat exchangers to
transfer heat from the working fluid to external processes (preheaters,
hot water tanks, etc.), reducing the workload on the enthalpy desorber
when cooling the controlled enclosure. If the system is running in
reverse to heat the controlled enclosure, heat exchangers can be used to
transfer heat from external sources into the working fluid to reduce the
workload of the enthalpy absorber.

[0058]For cooling applications that do not involve human habitation, other
phase change materials that have proper dielectric constant and dipole
moment such as ethanol can be substituted for the water. Other
atmospheres such as pure nitrogen or pure argon will also serve to
function as carrier for the phase change liquid.

[0059]Sensible and latent heat can be absorbed from air that is to be
conditioned through the use of the membrane based mass exchanger 100. The
mass exchanger 100 can absorb latent, moisture, heat directly from the
gas flow 102, such as an air stream that is in thermal communication with
air from within an enclosure and absorbs it into the liquid flow 104,
such as a first moving stream of cold water. Sensible, temperature, heat
is also absorbed by the membrane 110 and absorbed into the liquid flow
104, such as a moving stream of water that is in direct contact with the
membrane. This water-borne heat is transferred through a conventional
high surface area sensible exchanger such as a tube-in-tube or a spiral
coil to a gaseous refrigerant. The hot refrigerant then is mechanically
compressed raising its temperature.

[0060]The hot refrigerant then goes through another conventional sensible
exchanger such as a tube-in-tube or spiral coil transferring its heat to
a second stream of water. This second stream is circulated to a second
mass exchanger 100 that desorbs sensible and latent energy to an air
stream that is in thermal communication with the outside environment. The
cooled gaseous refrigerant is expanded through a valve and sent back to
the first mass exchanger 100, also known as an enthalpy exchanger. The
above process is repeated in a continuous fashion to efficiently
condition air with the enclosure.

[0061]The use of the mass exchangers 100 brings benefits besides the
improvements in efficiency. These benefits stem from the freedom to
locate and configure equipment as needed by the application. The
refrigerant is typically at high pressure necessitating metal piping and
welded joints. This calls for a high degree of skill and a time consuming
installation or repair. In one option, the compressor, expansion valve,
and two tube-in-tube liquid-to-liquid heat exchangers can be built in the
factory as a small, self-contained unit. When installed, the unit will
need only to be mechanically secured against the weather and vibration
and electrically powered. The mass exchangers 100 can be remotely located
where they are most effective or most convenient, needing only a
low-pressure water connection to make them functional. The refrigerant
unit can even be inside the structure with only the enthalpy desorber
located outside.

[0062]In the same fashion the mass exchangers 100 can also be located
where they are most convenient, preferably inside the conditioned space
where additional efficiencies are possible by reducing the duct losses
incurred circulating gas (typically air) throughout the enclosure. In the
broadest extension of the concept multiple mass exchangers 100 can be
located where they would be most effective, eliminating the need for a
central air ducting system entirely. This type of installation would
provide additional efficiencies in that unused or unoccupied spaces would
not be air conditioned until there was a requirement. A retrofit of
existing air conditioning systems can also be done such as shown in FIG.
11, where a mass exchanger 100 with hot water recovery can be added to an
existing air conditioner air handler unit and sensible coil.

Synergistic Additional Air Conditioning Functions

Heating

[0063]Since thermal energy is now being transported by water within the
air conditioning system, it is now possible to reverse the water
connections and create a heat pump. In this case the enthalpy absorber
would become an enthalpy desorber and the enthalpy desorber an enthalpy
absorber. Cold water would be circulated out of the enclosure to be
warmed by the sensible temperature heat and latent moisture heat from the
environment. This heat would then be concentrated and placed into the
interior enthalpy exchanger for distribution within the structure. The
compressor and refrigerant loop are unaffected by the change in pumping
direction. Back-up resistance heating is easily added for extreme weather
conditions and the interior enthalpy absorbers can be configured for a
sensible only thermal transfer when additional moisture is not needed
within the structure.

Thermal Storage

[0064]Use of water as a working fluid allows thermal storage strategies to
take advantage of variations in cost or availability of energy sources.
During periods of low thermal demand, the third (refrigerant) loop 187 is
used to create ice within the reservoir type heat exchanger (chilled
water reservoir) 188. When cooling demand resumes, this ice is used to
cool the first (chilled water) loop 184 without engaging the third
(refrigerant) loop 187.

System Reliability and Maintenance

[0065]Since the high pressure refrigerant loop can be made as a self
contained compact unit, the equipment can be tested and qualified at the
factory. This will reduce installation time by eliminating all tube
welding, leak checking and refrigerant pressurization. The factory
qualification of the equipment will also produce a more reliable system
by eliminating installation problems. In addition, the high-pressure
refrigerant loop equipment can be designed as a field replaceable part; a
part that is potentially customer serviceable. The elimination of the
majority of the high-pressure metal piping and sensible metal heat
exchangers will decrease the weight and lower the cost of the air
conditioning system.

Experimental Data

[0066]Two experimental prismatic plate enthalpy exchangers were designed
and built. The first exchanger consisted of 5 layers of the inventive
enthalpy membrane separated by machined PVC plastic flow fields. The
inventive enthalpy membrane comprised a statistically random ethylene
polystyrene co-polymer that was sulfonated to at least 35 mole %. The
design of the exchanger allowed air to flow unimpeded across the faces of
the membrane. Each membrane layer had an exchange area of approximately
508 cm (200 square inches). The membrane consisted of a 7 micron thick
coating of 35 mole % sulfonated, 70 weight % styrenic content, and random
block polymer ionomer adhered to 150 micron thick highly porous
polyethylene-silica microporous support. A flowing stream of water was
distributed across the ionomer face of the membrane. The flow rate is
expressed in fractional gallons per minute. The design of the exchanger
allowed air to flow unimpeded across the support side of the membrane.
Experimental data was gathered to show the exchange of moisture across
the membrane for various volumetric air flows.

[0068]As can be seen in the chart the enthalpy absorber cooled and
dehumidified the air while warming the water stream. This was done
without generating liquid water at the membrane air interface. At 86 cfm
the enthalpy absorber removed 18% of the water in the airstream.

[0070]As can be seen in chart, the enthalpy desorber cooled the water
stream while cooling and humidifying the air. This was done without
liquid water being present at the membrane air interface. At 67 cfm the
enthalpy desorber increased the amount of water in the air stream by 95%.

Example 3

[0071]A second enthalpy exchanger was built with 32 membrane layers each
with about 508 cm (200 square inches) of transfer area. The plastic PVC
flow fields were of a different design but the operational principles of
the second exchanger were identical to the first 5-membrane layer
exchanger. A test was run on this larger exchanger as an enthalpy
desorber. Here 32 degrees Celsius (90 degrees Fahrenheit) water was
pumped through the exchanger. The water flow was subdivided by the PVC
flow fields such that there was an even flow to each membrane; each
membrane receiving up to 11 gallons per minute of water flow. The water
flow rate was a variable in the test and is shown as the abscissa on the
chart below.

[0072]As shown in FIG. 14, plotted against the water flow rate were
several airflows of a known velocity, dry bulb temperature of 35 degrees
Celsius (95 degrees Fahrenheit) and humidity expressed a wet bulb
temperature of 14 degrees Celsius (58 degrees Fahrenheit) The thermal
energy of the absorber was calculated off of the temperature difference
between the inlet and outlet water. The face area of the enthalpy
exchanger was about 0.5 m (1.64 square feet) so that a volumetric air
flow rate could be reduced to a standard linear meter (feet) per minute
number. The air flow rate tested were about 60.96 meters (200 feet),
91.44 meters (300 feet), and about 121.92 meters (400 feet) per minute.

[0073]The incoming 32 degrees Celsius (90 degrees Fahrenheit) water was
cooled down to an outlet temperature of 17 to 26 degrees Celsius (63 to
79 degrees Fahrenheit) depending on the air flow and water flow rate. The
outlet water temperature is plotted against the left ordinate of the
chart. The energy difference between the incoming and exiting water is
plotted against the right ordinate of the chart.

[0074]The 32-membrane layer exchanger was able to transfer 3.5 to 7.5
kilowatts of thermal energy depending on water and air flow rates. The
enthalpy desorber exhibited a similar performance in terms of efficiency,
volumetric heat dissipation, and air flow to a large air conditioning
cooling tower but in a compact, easily maintained form.

Membranes

[0075]Certain embodiments disclosed herein relate to membrane-based
enthalpy exchangers which are utilized for absorbing and/or desorbing
sensible and/or latent heat into streams of moving liquid (such as water)
to transfer heat from within a target airspace (preferably an enclosed
target airspace) to the outside environment, or an exit airspace. The
membrane-based enthalpy exchange process is capable of bi-directional
operation, such that heat can also be brought into the target airspace
from the outside environment, or exit airspace. Thus, in certain
embodiments, the target airspace and exit airspace may be
interchangeable, depending on the desired goal and direction of operation
of the enthalpy exchange process.

[0077]A macromolecule, as used herein, generally refers to a molecule of
high relative molecular mass, the structure of which typically comprises
multiple repetition of segments derived from other molecules, such as for
certain oligomers, polymers, or co-polymers. The molecules utilized in at
least one membrane may be naturally occurring, artificial, or any
combination thereof. The molecules disclosed may be isolated or in a
mixture or solution and/or may be chemically synthesized.

[0078]As described inter alia, the molecules utilized in at least one
membrane disclosed herein may include, but are not limited to,
bio-polymers, oligomers and/or polymers, such as multiphase large
molecular chain polymers and/or copolymers. Particular embodiments
include, but are not limited to, (a) oligomers and/or polymers and/or
copolymers comprising an ion-containing polymer, (b) biopolymers, or (c)
block copolymers. In certain embodiments, molecules utilized in at least
one membrane described herein comprise an ion-containing oligomeric
segment or co-oligomeric segment (ionomer). Typically, ionomers utilized
in the present invention relate to polyelectrolyte polymers or copolymers
that contain both nonionic repeat units and at least a small amount of
ion containing repeating units.

[0079]Polymers of various degrees of polymerization are also included in
the membranes disclosed herein. As one of skill in the art would readily
appreciate, the degree of polymerization generally refers to the number
of repeat units or segments in an average polymer chain at a particular
time in a polymerization reaction, where length is measured by monomer
segments or units. Preferable lengths include, but are not limited to,
approximately 500 monomer units, 1000 monomer units, 5000 monomer units,
10,000 monomer units, 25,000 monomer units, 50,000 monomer units, 100,000
monomer units, 200,000 monomer units, 300,000 monomer units, 500,000
monomer units, 700,000 monomer units, or greater or any value there
between.

[0080]The degree of polymerization may also be a measure of the polymer's
molecular weight. Thus, the degree of polymerization is equal to the
total molecular weight of the polymer divided by the total molecular
weight of the repeating unit or segment. Polymers with different total
molecular weights but identical composition may exhibit different
physical properties. Generally, the greater the degree of polymerization
correlates with the greater melting temperature and greater mechanical
strength.

[0083]For purposes of this invention, an "arene-containing linear side
chain" refers to an unbranched hydrocarbon chain consisting only of
hydrogen or carbon, wherein at least one carbon in the chain is replaced
with an aryl or heteroaryl group, as defined above. For purposes of this
invention, a "non-arene-containing linear side chain" refers to an
unbranched hydrocarbon chain consisting only of hydrogen or carbon and
containing no aryl or heteroaryl groups within the chain. For purposes of
this invention, a "saturated linear side chain" refers to an unbranched
hydrocarbon chain consisting only of hydrogen or carbon comprising at
least one carbon-carbon double bond or at least one carbon-carbon triple
bond. An "unsaturated linear side chain," as used herein, generally
refers to an unbranched hydrocarbon chain consisting only of hydrogen or
carbon containing no carbon-carbon double bonds and no carbon-carbon
triple bonds.

[0084]For purposes of this invention, a "flexible hydrocarbon linear side
chain" refers to a flexible connecting component as taught by U.S. Pat.
Nos. 5,468,574 and 5,679,482, of which the disclosures of both are hereby
incorporated by reference in their entireties.

[0086]In other embodiments, the measurement of molecular weight may be
important. The average range of molecular weight (Mw) of the molecules
disclosed herein includes from about 20,000 grams/mole to about 1,000,000
grams/mole, and preferably from about 50,000 grams/mole to 900,000
grams/mole.

[0087]In general, ionomers utilized in the membranes of the invention
contain both polar and non-polar moieties. The nonpolar moieties of an
ionomer are grouped together, while the polar ionic moieties tend to
cluster together and separate from the nonpolar polymer backbone
moieties. This ionic moiety clustering allows for thermoplasticity of the
ionomers. Generally, when ionomers are heated, the ionic moieties will
lose their attraction for each other and the moieties will freely move,
thus allowing for thermoplastic elastomeric qualities of the ionic
polymer or copolymer.

[0088]Various types of copolymers, including block copolymers, exist that
may be used with the membranes of the invention. For example, alternating
copolymers comprise regular alternating A and B chemical or
constitutional units; periodic copolymers contain A and B units arranged
in a repeating sequence (e.g. (A-B-A-B-B-A-A-A-B-B)n); random
copolymers comprise random sequences of monomer A and B units;
statistical copolymers comprise an ordering of distinct monomers within
the polymer sequence that obeys statistical rules; block copolymers that
are comprised of two or more homopolymer subunits linked by covalent
bonds and may be diblock, tri-block, tetra-block or multi-block
copolymers. (IUPAC, Pure Appl. Chem., 68: 2287-2311 (1996)).

[0089]Additionally, any of the copolymers described may be linear
(comprising a single main chain), or branched (comprising a single main
chain with one or more polymeric side chains). Branched copolymers that
have side chains that are structurally distinct from the main chain are
known as graft copolymers. Individual chains of a graft copolymer may be
homopolymers or copolymers, and different copolymer sequencing is
sufficient to define a structural difference. For example, an A-B diblock
copolymer with A-B alternating copolymer side chains is considered a
graft copolymer. Other types of branched copolymers include star, brush
and comb copolymers. Any one of these copolymers, or any mixture thereof,
may be utilized with certain embodiments disclosed herein.

[0090]In certain embodiments disclosed herein, the molecule(s) utilized in
the membranes disclosed herein comprises a polymer comprised of at least
one block. In certain embodiments, the molecule is a thermoplastic block
copolymer. In other embodiments, the molecule is a block copolymer that
comprises differentiable monomeric units. Preferably, at least one of the
monomeric units of the block copolymer comprises an arene
moiety-containing unit. In other preferred embodiments, at least one
block comprises a non-arene moiety-containing unit. In certain
embodiments, the block copolymer comprises at least two monomeric units
arranged in statistically random order. In other embodiments, the block
copolymer comprises at least two monomeric units arranged in ordered
sequence. In certain embodiments, the molecule utilized in the processes
disclosed herein includes not only polymers or block copolymers, but also
copolymers with other ethylenically unsaturated monomers (such as
acrylonitrile, butadiene, methyl methacrylate, etc.).

[0091]In certain embodiments disclosed herein, a block copolymer refers to
a block copolymer having at least a first block of one or more mono
alkene-arene moiety, such as styrene, ring-substituted styrene,
α-substituted styrene, and any combination thereof; and a second
block of a controlled distribution copolymer of a diene moiety and a mono
alkene-arene moiety. The block copolymer can be any configuration of "A"
and "B" blocks, and such block copolymers can be generated by methods
known in the art.

[0092]For purposes of this invention, a "mono alkene-arene moiety" refers
to one or more alkene moieties, as defined above, covalently bonded to an
arene moiety, as defined above. An example of a "mono alkene-arene
moiety" is styrene. A "poly alkene-arene moiety" refers to a two or more
mono alkene-arene moieties, as defined above, covalently bonded to each
other to form a chain comprising two or more mono alkene-arene moieties.
An example of a "poly alkene-arene moiety" is polystyrene. A "diene
moiety" refers to a hydrocarbon chain containing two carbon-carbon double
bonds. In certain embodiments, the diene moiety may be conjugated,
unconjugated, or cumulated.

[0093]Some specific examples of block copolymers include those described
in U.S. Pat. Nos. 4,248,821; 5,239,010; 6,699,941; 7,186,779; 7,169,850;
7,169,848; 7,067,589; 7,001,950 and 6,699,941 and U.S. Patent Application
Publication Nos.: 20070021569; 20050154144; 20070004830; 20070020473;
20070026251; 20070037927; and 20070055015, all of which are hereby
incorporated by reference in their entireties.

[0094]In certain embodiments, the molecule comprises a statistical
copolymer. A statistical copolymer is used herein consistent with the
commonly understood usage in the art (see, for example, G. Odian,
Principles of Polymerization, 1991). Statistical copolymers are derived
from the simultaneous polymerization of two monomers and have a
distribution of the two monomeric units along the copolymer chain, which
follows Bernoullian (zero-order Markov), or first or second order Markov
statistics. The polymerization may be initiated by free radical, anionic,
cationic or coordinatively unsaturated (e.g., Ziegler-Natta catalysts)
species. According to Ring et al., (Pure Appl. Chem., 57, 1427, 1985),
statistical copolymers are the result of elementary processes leading to
the formation of a statistical sequence of monomeric units that do not
necessarily proceed with equal probability.

[0095]Statistical copolymers generally display a single glass transition
temperature. Block and graft copolymers typically display multiple glass
transitions, due to the presence of multiple phases. Statistical
copolymers are, therefore, distinguishable from block and graft
copolymers on this basis. The single glass transition temperature
typically reflects homogeneity at the molecular level. An additional
consequence of this homogeneity is that statistical copolymers, such as
those of styrene and butadiene, when viewed by electron microscopy,
display a single phase morphology with no microphase separation. By
contrast, block and graft copolymers of styrene/butadiene, for example,
are characterized by two glass transition temperatures and separation
into styrene-rich domains and butadiene-rich domains, particularly when
unmodified. It should be noted that membranes of the invention which are
produced from statistical copolymers originally having a single glass
transition temperature and a single phase morphology do not necessarily
exhibit a single phase morphology or a single glass transition
temperature after sulfonation or other modification.

[0096]Pseudo-random copolymers are a subclass of statistical copolymers
which result from a weighted change in the monomer incorporation that
skews the distribution from a random arrangement (i.e. Bernoullian) is
defined as statistical. Linear arrangements have been described here, but
branched or grafted including star arrangements of monomers are possible
as well. In addition, block copolymers of styrene and hydrogenated
butadiene, isoprene, or equivalent olefin can be employed. The block
architecture can be monomeric units comprising diblock, triblock,
graft-block, multi-arm starblock, multiblock, segmented, tapered block,
or any combination thereof.

[0097]One particular advantage provided by certain embodiments includes
the ability to apply the disclosed process to non-styrenic high molecular
weight polymers. Thus, in certain embodiments disclosed herein, the
molecules utilized in the membranes disclosed do not comprise a mono
alkene-arene moiety or segment, such as a styrene segment. In certain
other embodiments disclosed herein, polymers utilized in the processes
disclosed do not contain poly alkene-arene moieties or segments, such as
polystyrene. In certain such embodiments, the polymer includes moieties
or segments comprising unsaturated carbon-carbon double bonds, which are
able to be sulfonated. Some examples of such polymers include, but are
not limited to polybutadiene or polyisoprene.

[0098]In particular, certain embodiments disclosed herein relate to
membranes comprising molecules which have been modified (such as by
sulfonation, amidization, or other modification), the molecules
comprising one or more of the following moieties: alkane, alkene, alkyne,
and arene, each of which may be optionally substituted by one or more of
the following functional groups: carboxylic acid, urea, ester, urethane
(carbamate), alkene, amide, benzene, pyridine, indole, carbonate,
thioester, arcylate/acrylic, ether, amidine, ethyl, acid versions of
aliphatic compounds that contain alkenes, alkanes or alkynes, imidazole,
oxazole, and other possible combinations of heteroatom containing groups
susceptible to loss of water and/or disassembly. Each of the terms listed
above has its standard definition known to one skilled in the art.

[0100]In certain preferable embodiments, the membrane has no net charge,
but retains a high charge density comprising a balance of covalently
bound positive charges and free negative ions (for example, in the case
of sulfonation), or covalently bound negative charges and free positive
ions (for example, in the case of amidization). In certain preferable
embodiments, the membrane comprises an ionomeric polymer with an
equivalent acid weight of about 2500, about 2000, about 1500, about 1200,
about 1000, about 800, about 500, about 300, about 200, about 100, or
less, or any value therebetween. In certain embodiments, the ionomeric
polymer membranes exhibit high selectivity for water, and form uniform
thin structures that can be free standing or laminated to a support . In
certain embodiments, the ionomer polymers allow radiation or chemical
crosslinking to immobilize the molecules within the membrane and confer
particular mechanical and/or permeation properties.

[0103]Other examples of materials that may be utilized for the membranes
described herein are described in the following issued U.S. patents and
pending patent applications, all of which are incorporated by reference
in their entireties: U.S. Pat. Nos. 5,794,82; 5,468,574; 6,110,616;
6,413,294; 6,383,391; 6,413,298; 6,841,601; 7,179,860; and
PCT/US04/30936.

Support Structure

[0104]In one particular preferred embodiment, the at least one membrane
comprises a layer of ionomeric organic-inorganic hybrid polymers
optionally joined to at least one hydrophobic and/or hydrophilic support
structure, which provides physical and/or chemical reinforcement for the
membranes, in certain embodiments. In certain embodiments, the support
structure is absent. In certain embodiments, at least one support
structure is physically and/or chemically joined to the at least one
membrane(s). In certain embodiments, the support structure may be
hydrophobic and/or hydrophilic, or any combination of these, depending on
the specific requirements of the application and the desired goal.

[0105]In certain embodiments, the support structure may be porous, which
allows for the transfer of gas(es) across the support. The porosity of
the support structure can vary from about 5%, about 10%, about 20%, about
30%, about 40%, about 50%, about 60%, about 70%, about 80%, about 90%,
about 91 %, about 92%, about 93%, about 94%, about 95%, about 96%, about
97%, about 98%, about 99%, or greater or any value therebetween. In one
embodiment, the support structure comprises silica, in another
embodiment, the support structure comprises polyethylene silica. These
types of porous materials are available from companies such as W.L. Gore
(such as microfiltration media membranes), the Daramic Corporation
(polypropylene and polyethylene separators), and Sepro Membranes
(microfiltration membrane PVDF-MFB).

Phase-Change Materials

[0106]Any gas and/or liquid may be utilized in the HVAC system disclosed
herein. For example, for certain embodiments, phase change materials may
include liquid and/or gaseous forms of the following water, ethanol,
methanol, ammonia, and others. The materials utilized in the refrigerant
loop may include these as well as others, such as argon, nitrogen, carbon
dioxide, oxygen, hydrogen, helium, air, nitrous oxide,
chlorofluorocarbons (CFCs), neon, krypton, xenon, radon, haloalkanes,
methane, ammonia, sulfur dioxide, petroleum gas (including liquefied
petroleum gas (LPG)) (such as propane and/or butane), and any combination
of these. Certain of these phase change materials may release in the
heating and/or cooling process liquids and/or gases that may be harmful
to animals, including humans. Thus, certain of these phase-change
materials would be used for heating and/or cooling non-habitat airspace
(such as for cooling airspace containing electronic equipment).

Enthalpy Absorber

[0107]The enthalpy absorber increases the efficiency of the HVAC system in
a number of ways, such as by raising the refrigerant temperature required
to dehumidify and/or heat and/or cool the target airspace. The enthalpy
absorber described herein does not produce condensation in the typical
sense as occurs with HVAC systems presently on the market. Instead, vapor
(such as water vapor) is absorbed across the membrane and is condensed
directly into the moving liquid (e.g. water) stream on the other side of
the membrane. The lack of physical condensation on the membrane surface
results in continued transfer of additional moisture without blockage at
the membrane due to accumulation of condensation products. Furthermore,
moisture cannot re-evaporate back into the moving gas (e.g. air) stream.
The lack of droplet condensation and re-evaporation increases the net
effectiveness of the absorber. In addition, the absorber does not require
drip plates and/or water drains for condensation products due to the lack
of condensation on the membrane surface.

[0108]FIG. 15 is a psychometric chart that compares a sensible only a/c
evaporator and enthalpy absorber. In this example, using a 20% fresh air
mix, a sensible exchanger with a 7 degrees Celsius (45 degrees
Fahrenheit) water refrigerant yields a saturated air stream with a dry
bulb air reading of about 12.8 degrees Celsius (55 degrees Fahrenheit).
An enthalpy absorber will give a dry bulb reading of 11 degrees Celsius
(52 degrees Fahrenheit) at a relative humidity of 90%. Expressed in
enthalpy efficiency, the sensible condensing evaporator is 63% effective
and enthalpy absorber is 80% effective. Due to the high efficiency of the
enthalpy absorber evaporator, the temperature of the liquid (e.g. water)
refrigerant may be increased to about 12-13 degrees Celsius (55 degrees
Fahrenheit), which reduces the mechanical work required of the
compressor.

[0109]The ability of the enthalpy absorber to utilize water allows the
enthalpy absorber to be used in remote locations; not directly adjacent
to the compressor as is the common practice in today's small air
conditioning systems. The utilization of water also allows the absorber
function to be sub-divided into several smaller units which may be placed
wherever they are required. Thus, absorbers can be placed in every room
of a building, and each room could maintain an individual temperature and
humidity. Such individualized control has not previously been possible
with other HVAC systems, as extensive piping of the high-pressure
refrigerant and installation of water drains was required.

[0110]Further, direct control of humidity is possible with the hydronic
air conditioner of the invention. For example, by slowing the velocity of
the gas (e.g. air) stream, the absorber will dehumidify the gas (e.g.
air) down to the wet bulb temperature of the cool liquid (e.g. water)
stream, removing humidity from the gas (e.g. air). This allows for
humidity control of each room in a building or other target airspace to
be controlled by regulating the velocity of the gas (e.g. air) and the
liquid (e.g. water) stream temperature through the enthalpy exchanger.

Enthalpy Desorber

[0111]The enthalpy desorber provides for desorption of moisture from a
moving stream of liquid (i.e. water) that has a higher temperature than
the wet bulb temperature of the moving gas (e.g. air) stream in contact
with the membrane. Each enthalpy desorber comprises at least one membrane
that separates a moving stream of liquid (water) and a moving stream of
gas (e.g. air). In certain embodiments, the ionomeric polymer membrane
layer and optional support structure creates a selectively permeable
barrier. At least one membrane has the ability to exclude many airborne
organic and inorganic particulates and gases, while selectively
transferring liquids (e.g. water). Thus, the membrane allows for
desorption of moisture from a moving stream of liquid (e.g. water) that
has a higher temperature than the dew point of the moving gas (e.g. air)
stream in contact with the membrane.

[0112]The membrane reduces required maintenance for the HVAC system, since
the membrane protects the refrigerant liquid (e.g. water) from
contamination and the preferred embodiment of the membrane reduces or
eliminates the need for chemicals to prevent microbiological
contamination (such as, microbes including mold and/or bacterial growth).
The average dissolved solids content of the circulating liquid (salts
and/or metals and/or other agents) is maintained below concentrations
that leave scale or deposits, and the steady flow of liquid past the
membrane eliminates local stagnant regions common to surface evaporators,
ensuring the liquid never evaporates completely and deposits solids on
the heat transfer surface that force maintenance. In addition, the
enthalpy absorber absorbs moisture from the target airspace and produces
membrane-filtered water that can be recovered and pumped back into the
reservoir of the hot water loop, which reduces the concentration of
dissolved solids circulating through the enthalpy desorber. In certain
embodiments, the membrane-filtered water may be free from dissolved
solids, microorganisms, and other biological and/or chemical impurities.
This control over concentration levels and evaporation surfaces allows
significant reduction or preferably elimination of anti-scaling additives
in the liquid without the creation of local deposits.

[0113]At these concentrations, the vapor pressure of the fluid is not
greatly affected by solids content and the ability of the membrane to
transport moisture is largely independent of the dissolved solids
content. Thus, variations of dissolved solids within the liquid (i.e.
water) do not impair the membrane's capabilities, and the reduction in
chemical additives used to control biological fouling, scale, and
deposits allows for disposal of the circulating water in a municipal
drain.

Heating a Target Airspace

[0114]As disclosed in other sections elsewhere herein, thermal energy is
transported by liquid (i.e. water) within the HVAC system, thus it is
possible to reverse the liquid (i.e. water) connections, thereby creating
a heat pump from the HVAC system. In this case, the enthalpy absorber and
desorber would reverse roles (that is, the enthalpy desorber becomes an
enthalpy absorber, and vice versa). In one exemplary embodiment, cold
liquid (such as water) would be warmed by the sensible heat and latent
moisture heat from the outside environment or exit airspace. This heat
could be concentrated and placed into the interior enthalpy exchanger for
distribution within the target airspace. The compressor and refrigerant
loop are unaffected by the change in pumping direction. In other
embodiments, the interior enthalpy absorbers can be configured for a
sensible only thermal transfer when additional moisture is not needed
within the target airspace.

[0115]All of the above U.S. patents, U.S. patent application publications,
U.S. patent applications, foreign patents, foreign patent applications
and non-patent publications referred to in this specification and/or
listed in the Application Data Sheet, are incorporated by reference in
their entireties.

[0116]From the foregoing it will be appreciated that, although specific
embodiments of the invention have been described herein for purposes of
illustration, various modifications may be made without deviating from
the spirit and scope of the invention.